Jakob Hartbrich

dblp:362/2454 · DBLP profile ↗
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7ranked-venue papers
2as first author
7since 2021 · last 2026
0009-0005-2074-5899ORCID · verified

Domains — the database's venue-derived domains; a paper can count in several

Human-computer interaction and ubiquitous computing · 6 · 1 first-author · 6 since 2021Graphics, computer vision, multimedia, augmented reality and games · 5 · 1 first-author · 5 since 2021
YearPublicationVenuePosition
2026 Exploring Mediated Communication with Older Adults: Comparing AR Avatars, Telepresence Robots, and Face-to-Face Interaction
abstract
Older adults, a growing demographic, face an increased risk of experiencing loneliness and are less exposed to emerging communication technologies. Augmented reality (AR) avatars and telepresence robots have been proposed as tools to foster social connection, yet their suitability for older users remains underexplored. We present an exploratory study with ten healthy older adults who engaged in both conversational and spatial collaboration tasks using AR avatar-mediated communication, robot-mediated communication, and face-to-face interaction. We collected self-reported measures of co-presence, social presence, closeness, uncanny valley, preferences, and open feedback. Our findings suggest that telepresence robots enhanced co-presence, while avatars were valued for their expressivity and humanlike qualities. Task type influenced co-presence in spatial collaboration only during communication using the telepresence robot. Other measures, such as social presence and closeness, were unaffected by task type or representation. While neither technology outperformed face-to-face interaction, both were positively received, underscoring their potential to address the social needs of older adults and highlighting the importance of enhancing nonverbal expressivity, particularly nonverbal cues in mediated communication. Ultimately, our results contribute to the fundamental understanding of mediated communication with older adults, motivating further empirical work to confirm and extend these findings.
Stephanie Arevalo, Jakob Hartbrich, Florian Weidner, Melisa Conde, Veronika Mikhailova, Felix Immohr, Söhnke Benedikt Fischedick, Bea Vorhof, Christoph Gerhardt, Kay Richter, Christian Kunert, Nicola Döring, Horst-Michael Groß, Wolfgang Broll, Alexander Raake
IMX2
2025 Robot, Avatar, or Human: The Impact of Partner Representation and Task on the Communication Experience
abstract
Avatars and telepresence robots have long received attention for remote communication. However, the specific nature of their physicality, expressiveness, and mobility may affect their usefulness for different tasks. This work compares using an avatar (presented in augmented reality) and a telepresence robot to Face-to-Face (F2F) communication during different communication tasks: free conversation, negotiation, and referential communication with movement. We conducted a user study (split-plot design, N=54) with the type of representation of the conversational partner as the within variable and the communication task as the between variable. Our results show that the type of task, especially referential communication with movement, influenced the perceived attention to nonverbal cues and closeness. Generally, gestures and body movements received the least focus with telepresence robots. Gestures in avatars and F2F drew similar attention, which we attribute to the avatar's tracking fidelity. Gaze received less attention in both avatar- and robot-mediated communication compared to F2F, while facial expressions on the robot's screen heightened attention compared to avatars. These findings advance the fundamental understanding of mediated communication and support researchers and practitioners in shaping the design of communication applications beyond today's video calls.
Stephanie Arevalo, Jakob Hartbrich, Florian Weidner, Söhnke Benedikt Fischedick, Christoph Gerhardt, Kay Richter, Christian Kunert, Bea Vorhof, Horst-Michael Groß, Wolfgang Broll, Alexander Raake
Proc. ACM Hum. Comput. Interact.2
2025 The Effect of Hand Visibility in AR: Comparing Dexterity and Interaction with Virtual and Real Objects
abstract
Hand-tracking technologies allow us to use our own hands to interact with real and virtual objects in Augmented Reality (AR) environments. This enables us to explore the interplay between hand-visualizations and hand-object interactions. We present a user study that examines the effect of different hand visualizations (invisible, transparent, opaque) on manipulation performance when interacting with real and virtual objects. For this, we implemented video-see-through (VST) AR-based virtual building blocks and hot wire tasks with real one-to-one counterparts that require participants to use gross and fine motor hand movements. To evaluate manipulation performance, we considered three measures: task completion time, number of collisions (hot wire task), and percentage of object displacement (building block task). Additionally, we explored the sense of agency and subjective impressions (preference, ease of interaction, successful and awkwardness) evoked by the different hand-visualizations. The results show that (1) manipulation performance is significantly higher when interacting with real objects compared to virtual ones, (2) invisible hands lead to fewer errors, higher agency, higher perceived success and ease of interaction during fine manipulation tasks with real objects, and (3) having some visualization of the virtual hands (transparent or opaque) overlayed on the real hands is preferred when manipulating virtual objects even when there are no significant performance improvements. Our empirical findings about the differences when interacting with real and virtual objects can aid hand visualization choices for manipulation tasks in AR.
Jakob Hartbrich, Stephanie Arevalo, Steve Goering, Alexander Raake
IEEE Trans. Vis. Comput. Graph.1
2024 Eyes on the Narrative: Exploring the Impact of Visual Realism and Audio Presentation on Gaze Behavior in AR Storytelling
abstract
Augmented Reality (AR) and Virtual Reality (VR) are essential tools for researchers and practitioners, serving purposes from training to entertainment: many of these applications rely on agents. This study explores the impact of agent characteristics on user reactions, focusing on gaze as a primary visual attention indicator in AR and VR. While existing research has investigated the agent’s gaze and its influence on the user, it is unclear how the agent’s auralization and visualization influence gaze behaviour. We investigate this by studying the impact of rendering style and type of audio on gaze behaviour during a narrative AR experience. Participants listened to a story with the agent visualized as a cartoon-style or realistic virtual human and auralized with spatial or non-spatial audio. The results revealed that the agent’s rendering style significantly influenced gaze behaviour, with cartoon-style agents capturing more visual attention. Audio variations did not yield significant differences. Together, our findings inform the design of AR user interfaces with agents, suggesting that low-realism visualizations are more captivating and, thus, more suitable for experiences where the user is supposed to look at the storyteller.
Florian Weidner, Jakob Hartbrich, Stephanie Arevalo, Christian Kunert, Christian Schneiderwind, Chenyao Diao, Christoph Gerhardt, Tatiana Surdu, Wolfgang Broll, Stephan Werner 0003, Alexander Raake
ETRA2
2024 Work-in-Progress: Older Adults' Experiences With an Augmented Reality Communication System
abstract
Given the profound impact of staying socially connected on the well-being of older adults, this study explores the potential of augmented reality (AR) systems to enrich their social lives. A wearable AR communication system prototype was developed and tested in a user study involving N = 16 older adults from Germany. Participants wore an AR headset and engaged in a conversation task with a remote person represented by an avatar. Older adults’ experiences were assessed using think-aloud protocols, qualitative observations, posttest questionnaires, and semi-structured oral interviews. Preliminary findings indicate overall participant satisfaction, with minimal observed difficulties in headset usage and avatar-mediated interpersonal communication. The positive engagement during AR conversations highlights the system’s potential to provide positive communication experiences among older individuals. This work-in-progress paper introduces the developed system prototype and outlines the conducted user study. Further data analyses will provide deeper insights into older adults’ experiences with the system. The results will contribute to refining the prototype and offer valuable insights for the development of AR communication systems tailored to the needs and preferences of older adults.
Veronika Mikhailova, Christian Kunert, Jakob Hartbrich, Tobias Schwandt, Christoph Gerhardt, Alexander Raake, Wolfgang Broll, Nicola Döring
IMX3
2024 Beyond Looks: A Study on Agent Movement and Audiovisual Spatial Coherence in Augmented Reality
abstract
The appearance of virtual humans (avatars and agents) has been widely explored in immersive environments. However, virtual humans’ movements and associated sounds in real-world interactions, particularly in Augmented Reality (AR), are yet to be explored. In this paper, we investigate the influence of three distinct movement patterns (circle, side-to-side, and standing), two rendering styles (realistic and cartoon), and two types of audio (spatial audio and non-spatial audio) on emotional responses, social presence, appearance and behavior plausibility, audiovisual coherence, and auditory plausibility. To enable that, we conducted a study (N=36) where participants observed an agent reciting a short fictional story. Our results indicate an effect of the rendering style and the type of movement on the subjective perception of the agents behaving in an AR environment. Participants reported higher levels of excitement when they observed the realistic agent moving in a circle compared to the cartoon agent or the other two movement patterns. Moreover, we found an influence of agent’s movement pattern on social presence and higher appearance and behavior plausibility for the realistic rendering style. Regarding audiovisual spatial coherence, we found an influence of rendering style and type of audio only for the cartoon agent. Additionally, the spatial audio was perceived as more plausible than non-spatial audio. Our findings suggest that aligning realistic rendering styles with realistic auditory experiences may not be necessary for 1-1 listening experiences with moving sources. However, movement patterns of agents influence excitement and social presence in passive unidirectional communication scenarios.
Stephanie Arevalo, Christian Kunert, Jakob Hartbrich, Christian Schneiderwind, Chenyao Diao, Christoph Gerhardt, Tatiana Surdu, Florian Weidner, Wolfgang Broll, Stephan Werner 0003, Alexander Raake
VR3
2023 Eye and Face Tracking in VR: Avatar Embodiment and Enfacement with Realistic and Cartoon Avatars
abstract
Previous studies have explored the perception of various types of embodied avatars in immersive environments. However, the impact of eye and face tracking with personalized avatars is yet to be explored. In this paper, we investigate the impact of eye and face tracking on embodiment, enfacement, and the uncanny valley with four types of avatars using a VR-based mirroring task. We conducted a study (N=12) and created self-avatars with two rendering styles: a cartoon avatar (created in an avatar generator using a picture of the user’s face) and a photorealistic scanned avatar (created using a 3D scanner), each with and without eye and face tracking and respective adaptation of the mirror image. Our results indicate that adding eye and face tracking can be beneficial for certain enfacement scales (belonged), and we confirm that compared to a cartoon avatar, a scanned realistic avatar results in higher body ownership and increased enfacement (own face, belonging, mirror) — regardless of eye and face tracking. We critically discuss our experiences and outline the limitations of the applied hardware and software with respect to the provided level of control and the applicability for complex tasks such as displaying emotions. We synthesize these findings into a discussion about potential improvements for facial animation in VR and highlight the need for a better level of control, the integration of additional sensing and processing technologies, and an objective metric for comparing facial animation systems.
Jakob Hartbrich, Florian Weidner, Christian Kunert, Alexander Raake, Wolfgang Broll, Stephanie Arevalo
MUM1